// Copyright 2017 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_GEOMETRIC_NORMAL_ENCODER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_GEOMETRIC_NORMAL_ENCODER_H_

#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_encoder.h"
#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_geometric_normal_predictor_area.h"
#include "draco/compression/config/compression_shared.h"
#include "draco/core/bit_coders/rans_bit_encoder.h"

namespace draco {

// Prediction scheme for normals based on the underlying geometry.
// At a smooth vertices normals are computed by weighting the normals of
// adjacent faces with the area of these faces. At seams, the same approach
// applies for seam corners.
template <typename DataTypeT, class TransformT, class MeshDataT>
class MeshPredictionSchemeGeometricNormalEncoder
    : public MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT> {
  public:
    using CorrType = typename MeshPredictionSchemeEncoder<DataTypeT, TransformT,
          MeshDataT>::CorrType;
    MeshPredictionSchemeGeometricNormalEncoder(const PointAttribute *attribute,
            const TransformT &transform,
            const MeshDataT &mesh_data)
        : MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT>(
              attribute, transform, mesh_data),
          predictor_(mesh_data) {}

    bool ComputeCorrectionValues(
        const DataTypeT *in_data, CorrType *out_corr, int size,
        int num_components, const PointIndex *entry_to_point_id_map) override;

    bool EncodePredictionData(EncoderBuffer *buffer) override;

    PredictionSchemeMethod GetPredictionMethod() const override {
        return MESH_PREDICTION_GEOMETRIC_NORMAL;
    }

    bool IsInitialized() const override {
        if (!predictor_.IsInitialized())
            return false;
        if (!this->mesh_data().IsInitialized())
            return false;
        return true;
    }

    int GetNumParentAttributes() const override {
        return 1;
    }

    GeometryAttribute::Type GetParentAttributeType(int i) const override {
        DRACO_DCHECK_EQ(i, 0);
        (void)i;
        return GeometryAttribute::POSITION;
    }

    bool SetParentAttribute(const PointAttribute *att) override {
        if (att->attribute_type() != GeometryAttribute::POSITION)
            return false;  // Invalid attribute type.
        if (att->num_components() != 3)
            return false;  // Currently works only for 3 component positions.
        predictor_.SetPositionAttribute(*att);
        return true;
    }

  private:
    void SetQuantizationBits(int q) {
        DRACO_DCHECK_GE(q, 2);
        DRACO_DCHECK_LE(q, 30);
        octahedron_tool_box_.SetQuantizationBits(q);
    }
    MeshPredictionSchemeGeometricNormalPredictorArea<DataTypeT, TransformT,
                                                     MeshDataT>
                                                     predictor_;

    OctahedronToolBox octahedron_tool_box_;
    RAnsBitEncoder flip_normal_bit_encoder_;
};

template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeGeometricNormalEncoder<DataTypeT, TransformT,
     MeshDataT>::
     ComputeCorrectionValues(const DataTypeT *in_data, CorrType *out_corr,
                             int size, int num_components,
const PointIndex *entry_to_point_id_map) {
    this->SetQuantizationBits(this->transform().quantization_bits());
    predictor_.SetEntryToPointIdMap(entry_to_point_id_map);
    DRACO_DCHECK(this->IsInitialized());
    // Expecting in_data in octahedral coordinates, i.e., portable attribute.
    DRACO_DCHECK_EQ(num_components, 2);

    flip_normal_bit_encoder_.StartEncoding();

    const int corner_map_size = this->mesh_data().data_to_corner_map()->size();

    VectorD<int32_t, 3> pred_normal_3d;
    VectorD<int32_t, 2> pos_pred_normal_oct;
    VectorD<int32_t, 2> neg_pred_normal_oct;
    VectorD<int32_t, 2> pos_correction;
    VectorD<int32_t, 2> neg_correction;
    for (int data_id = 0; data_id < corner_map_size; ++data_id) {
        const CornerIndex corner_id =
            this->mesh_data().data_to_corner_map()->at(data_id);
        predictor_.ComputePredictedValue(corner_id, pred_normal_3d.data());

        // Compute predicted octahedral coordinates.
        octahedron_tool_box_.CanonicalizeIntegerVector(pred_normal_3d.data());
        DRACO_DCHECK_EQ(pred_normal_3d.AbsSum(),
                        octahedron_tool_box_.center_value());

        // Compute octahedral coordinates for both possible directions.
        octahedron_tool_box_.IntegerVectorToQuantizedOctahedralCoords(
            pred_normal_3d.data(), pos_pred_normal_oct.data(),
            pos_pred_normal_oct.data() + 1);
        pred_normal_3d = -pred_normal_3d;
        octahedron_tool_box_.IntegerVectorToQuantizedOctahedralCoords(
            pred_normal_3d.data(), neg_pred_normal_oct.data(),
            neg_pred_normal_oct.data() + 1);

        // Choose the one with the best correction value.
        const int data_offset = data_id * 2;
        this->transform().ComputeCorrection(in_data + data_offset,
                                            pos_pred_normal_oct.data(),
                                            pos_correction.data());
        this->transform().ComputeCorrection(in_data + data_offset,
                                            neg_pred_normal_oct.data(),
                                            neg_correction.data());
        pos_correction[0] = octahedron_tool_box_.ModMax(pos_correction[0]);
        pos_correction[1] = octahedron_tool_box_.ModMax(pos_correction[1]);
        neg_correction[0] = octahedron_tool_box_.ModMax(neg_correction[0]);
        neg_correction[1] = octahedron_tool_box_.ModMax(neg_correction[1]);
        if (pos_correction.AbsSum() < neg_correction.AbsSum()) {
            flip_normal_bit_encoder_.EncodeBit(false);
            (out_corr + data_offset)[0] =
                octahedron_tool_box_.MakePositive(pos_correction[0]);
            (out_corr + data_offset)[1] =
                octahedron_tool_box_.MakePositive(pos_correction[1]);
        } else {
            flip_normal_bit_encoder_.EncodeBit(true);
            (out_corr + data_offset)[0] =
                octahedron_tool_box_.MakePositive(neg_correction[0]);
            (out_corr + data_offset)[1] =
                octahedron_tool_box_.MakePositive(neg_correction[1]);
        }
    }
    return true;
}

template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeGeometricNormalEncoder<
DataTypeT, TransformT, MeshDataT>::EncodePredictionData(EncoderBuffer
        *buffer) {
    if (!this->transform().EncodeTransformData(buffer))
        return false;

    // Encode normal flips.
    flip_normal_bit_encoder_.EndEncoding(buffer);
    return true;
}

}  // namespace draco

#endif  // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_GEOMETRIC_NORMAL_ENCODER_H_
